aimux-core 0.5.0

//! User-facing API: `generate_text` and `stream_text`.
//!
//! These are the primary entry points for users. They:
//! 1. Convert user prompt (`ModelPrompt`) to `LanguageModelPrompt` (provider-facing).
//! 2. Build `CallOptions` from user-facing options.
//! 3. Call `LanguageModel::do_generate` / `do_stream`.
//! 4. Extract / wrap the result for the user.

use std::collections::HashMap;
use std::pin::Pin;
use std::time::Instant;

use futures::{Stream, StreamExt};
use serde::{Deserialize, Serialize};
use serde_json::Value;
use tracing::Instrument;
use ts_rs::TS;

use crate::error::AiMuxError;
use crate::language_model::LanguageModel;
use crate::language_model_message::convert_to_language_model_prompt;
use crate::message::{ModelMessage, ModelPrompt};
use crate::options::{CallOptions, ResponseFormat, ToolChoice};
use crate::parse_tool_call::{RawToolCall, ToolCallRepair, parse_tool_call};
use crate::result::{
    FilePart, GenerateContent, GenerateResult, ReasoningPart, SourcePart, StreamResult,
    StreamTextResultAggregated,
};
use crate::stream_part::StreamPart;
use crate::tool::Tool;
use crate::types::{FinishReason, ReasoningEffort, Usage, Warning};
use crate::{AbortSignal, retry, timeout};

/// Matches the AI SDK's `isOutputChunk`: only chunks containing model output
/// start or reset the first/chunk output timers.
fn is_output_chunk(part: &StreamPart) -> bool {
    match part {
        StreamPart::TextDelta { delta, .. }
        | StreamPart::ReasoningDelta { delta, .. }
        | StreamPart::ToolInputDelta { delta, .. } => !delta.is_empty(),
        StreamPart::ToolCall { .. } | StreamPart::File { .. } => true,
        _ => false,
    }
}

// ─────────────────────────────────────────────────────────────────────────────
// User-facing options
// ─────────────────────────────────────────────────────────────────────────────

/// User-facing options for `generate_text` and `stream_text`.
///
/// Unlike `CallOptions` (provider-facing), this does not include `prompt`
/// (passed separately) and defaults are more ergonomic.
#[derive(Debug, Clone, Default, Serialize, Deserialize, TS)]
#[ts(export)]
pub struct GenerateTextOptions {
    pub max_output_tokens: Option<u32>,
    pub temperature: Option<f64>,
    pub stop_sequences: Option<Vec<String>>,
    pub top_p: Option<f64>,
    pub top_k: Option<f64>,
    pub presence_penalty: Option<f64>,
    pub frequency_penalty: Option<f64>,
    pub response_format: Option<ResponseFormat>,
    #[ts(type = "number | null")]
    pub seed: Option<u64>,
    pub tools: Option<Vec<Tool>>,
    pub tool_choice: Option<ToolChoice>,
    pub headers: Option<HashMap<String, String>>,
    pub provider_options: Option<HashMap<String, Value>>,
    /// Top-level reasoning effort.
    pub reasoning: Option<ReasoningEffort>,
    /// System instructions prepended to the prompt.
    pub instructions: Option<String>,
    /// Per-call request body overrides (deep-merged). See RFC-0017.
    pub body_overrides: Option<Value>,
    /// Per-call retry count override. `None` = provider default, `Some(0)` = disable.
    pub max_retries: Option<u32>,
    /// Per-call timeout configuration (total / first-chunk / chunk idle).
    pub timeout: Option<crate::options::TimeoutConfiguration>,
    /// Session identifier, for grouping consecutive calls into a session
    /// (observability, see RFC-0024). Orthogonal to RFC-0019 session-affinity
    /// headers. When `None` and the optional session inferer is enabled, one
    /// may be inferred from prompt-prefix continuation.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub session_id: Option<String>,
    /// Abort signal for cancelling the call.
    ///
    /// Runtime handle — never crosses the JSON boundary. Rust callers set it
    /// directly; the Node binding bridges a JS `AbortSignal` natively.
    #[serde(skip)]
    #[ts(skip)]
    pub abort_signal: Option<AbortSignal>,
    /// Emit raw provider stream chunks as `StreamPart::Raw` (debugging aid).
    pub include_raw_chunks: Option<bool>,
    /// Optional one-shot repair callback for unknown, malformed, or
    /// schema-invalid tool calls.
    #[serde(skip)]
    #[ts(skip)]
    pub repair_tool_call: Option<ToolCallRepair>,
}

impl GenerateTextOptions {
    /// Build the provider-facing `CallOptions` from user-facing options.
    #[must_use]
    pub fn into_call_options(
        self,
        prompt: crate::language_model_message::LanguageModelPrompt,
    ) -> CallOptions {
        CallOptions {
            prompt,
            max_output_tokens: self.max_output_tokens,
            temperature: self.temperature,
            stop_sequences: self.stop_sequences,
            top_p: self.top_p,
            top_k: self.top_k,
            presence_penalty: self.presence_penalty,
            frequency_penalty: self.frequency_penalty,
            response_format: self.response_format,
            seed: self.seed,
            tools: self.tools,
            tool_choice: self.tool_choice.unwrap_or_default(),
            headers: self.headers,
            provider_options: self.provider_options,
            reasoning: self.reasoning,
            body_overrides: self.body_overrides,
            max_retries: self.max_retries,
            timeout: self.timeout,
            session_id: self.session_id,
            abort_signal: self.abort_signal,
            call_id: None,
            recording_context: None,
            include_raw_chunks: self.include_raw_chunks,
        }
    }
}

// ─────────────────────────────────────────────────────────────────────────────
// User-facing result types
// ─────────────────────────────────────────────────────────────────────────────

/// Result of `generate_text` (user-facing).
#[derive(Debug, Serialize, Deserialize, TS)]
#[ts(export)]
pub struct GenerateTextResult {
    /// The generated text (concatenated from all text content parts).
    pub text: String,
    /// Tool calls requested by the model.
    pub tool_calls: Vec<crate::tool::ToolCall>,
    /// Why generation stopped.
    pub finish_reason: FinishReason,
    /// Token usage.
    pub usage: Usage,
    /// Warnings from the provider.
    pub warnings: Vec<Warning>,
    /// Raw provider result (for advanced use).
    pub raw: GenerateResult,
    // ── M7: top-level aggregation (extracted from `raw.content`) ──
    /// Reasoning / thinking segments from the model.
    #[serde(default)]
    pub reasoning: Vec<ReasoningPart>,
    /// Concatenated reasoning text (convenience for `reasoning.iter().map(text).join("")`).
    #[serde(default)]
    pub reasoning_text: String,
    /// Sources / citations (search-preview models).
    #[serde(default)]
    pub sources: Vec<SourcePart>,
    /// Files generated by the model.
    #[serde(default)]
    pub files: Vec<FilePart>,
    /// Assistant messages ready to append to the prompt for the next turn
    /// (solves the multi-turn "manually build assistant message" footgun).
    #[serde(default)]
    pub response_messages: Vec<ModelMessage>,
    /// The raw provider-specific finish reason string (e.g. "stop",
    /// "end_turn", "safety"). Useful when `finish_reason.unified` is `Other`.
    #[serde(default)]
    pub raw_finish_reason: Option<String>,
    /// Provider-specific metadata (e.g. Anthropic cache info). Mirrored from
    /// `raw.provider_metadata` for top-level convenience.
    #[serde(default)]
    pub provider_metadata: Option<Value>,
    /// Response metadata (id, timestamp, model_id). Mirrored from
    /// `raw.response` for top-level convenience.
    #[serde(default)]
    pub response: crate::types::ResponseMetadata,
    /// Total token usage across all steps. In single-step mode (aimux's
    /// default), `total_usage` equals `usage`. Provided for AI SDK parity.
    #[serde(default)]
    pub total_usage: Usage,
}

/// Result of `generate_object` (user-facing, M12). The parsed JSON object plus
/// convenience fields from the underlying `generate_text` call.
#[derive(Debug, Serialize, Deserialize, TS)]
#[ts(export)]
pub struct GenerateObjectResult {
    /// The parsed JSON object returned by the model.
    pub object: Value,
    /// Why generation stopped.
    pub finish_reason: FinishReason,
    /// Raw provider-specific finish reason string.
    #[serde(default)]
    pub raw_finish_reason: Option<String>,
    /// Token usage.
    pub usage: Usage,
    /// Warnings from the provider.
    pub warnings: Vec<Warning>,
    /// Concatenated reasoning text (if the model produced reasoning/thinking).
    #[serde(default)]
    pub reasoning: Option<String>,
    /// Provider-specific metadata (e.g. Anthropic cache info).
    #[serde(default)]
    pub provider_metadata: Option<Value>,
    /// Response metadata (id, timestamp, model_id).
    #[serde(default)]
    pub response: crate::types::ResponseMetadata,
    /// The full `generate_text` result (for advanced use).
    pub raw: GenerateTextResult,
}

/// Result of `stream_text` (user-facing).
pub struct StreamTextResult {
    /// The stream of `StreamPart` items.
    pub stream: Pin<Box<dyn Stream<Item = Result<StreamPart, AiMuxError>> + Send>>,
    /// The request body that was sent (for debugging / cache probing, RFC-0015).
    pub request_body: Option<serde_json::Value>,
    /// Response headers.
    pub response_headers: Option<HashMap<String, String>>,
}

impl std::fmt::Debug for StreamTextResult {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("StreamTextResult")
            .field("stream", &"<stream>")
            .field("request_body", &self.request_body)
            .field("response_headers", &self.response_headers)
            .finish()
    }
}

impl StreamTextResult {
    /// Consume the stream and collect all text deltas into a single `String`.
    ///
    /// # Errors
    ///
    /// Returns the stream's error part or transport error, propagated from the
    /// underlying model stream.
    pub async fn text(self) -> Result<String, AiMuxError> {
        let mut result = String::new();
        let mut saw_output = false;
        let mut saw_finish = false;
        let mut provider_error: Option<AiMuxError> = None;
        let mut stream = self.stream;
        while let Some(part) = stream.next().await {
            let part = match part {
                Ok(part) => part,
                // A recoverable frame error is data on this stream (core keeps
                // the stream alive past it); fold it into the same first-error
                // slot as a provider error event and keep consuming so the
                // trailing Finish still lands (usage, recording).
                Err(error) if error.is_recoverable_stream_error() => {
                    if provider_error.is_none() {
                        provider_error = Some(error);
                    }
                    continue;
                }
                Err(error) => return Err(error),
            };
            if is_output_chunk(&part) {
                saw_output = true;
            }
            match part {
                StreamPart::TextDelta { delta, .. } => result.push_str(&delta),
                StreamPart::Finish { .. } => {
                    saw_finish = true;
                    break;
                }
                // Keep consuming after a provider error event: a trailing
                // Finish still carries usage for the recording layer. The
                // error is returned once the stream reaches its end.
                StreamPart::Error { error } if provider_error.is_none() => {
                    provider_error = Some(error);
                }
                _ => {}
            }
        }
        if let Some(error) = provider_error {
            return Err(error);
        }
        // AI SDK semantics: an incomplete stream with no output at all is an
        // error; an incomplete stream with partial output retains the partial
        // result.
        if !saw_finish && !saw_output {
            return Err(AiMuxError::InvalidResponseData(
                "No output generated. The model stream ended without a finish chunk.".into(),
            ));
        }
        Ok(result)
    }

    /// Consume the full stream and return an aggregated result (M11).
    ///
    /// Unlike [`text`](Self::text) (which returns only the concatenated text),
    /// this collects reasoning, tool calls, sources, files, usage, finish
    /// reason, and builds `response_messages` for the next turn.
    ///
    /// # Errors
    ///
    /// Returns the stream's error part or transport error, propagated from the
    /// underlying model stream.
    pub async fn consume(self) -> Result<StreamTextResultAggregated, AiMuxError> {
        let mut text = String::new();
        let mut tool_calls: Vec<crate::tool::ToolCall> = Vec::new();
        let mut sources: Vec<SourcePart> = Vec::new();
        let mut files: Vec<FilePart> = Vec::new();
        let mut warnings: Vec<Warning> = Vec::new();
        let mut finish_reason = FinishReason {
            unified: crate::types::FinishReasonUnified::Stop,
            raw: None,
        };
        let mut raw_finish_reason: Option<String> = None;
        let mut usage = Usage::default();
        let mut finish_provider_metadata: Option<Value> = None;
        let mut response: Option<crate::types::ResponseMetadata> = None;
        let mut rm = crate::response_messages::ResponseMessageBuilder::new();

        let mut saw_output = false;
        let mut saw_finish = false;
        let mut provider_error: Option<AiMuxError> = None;
        let mut stream = self.stream;
        while let Some(part) = stream.next().await {
            let part = match part {
                Ok(part) => part,
                // A recoverable frame error is data on this stream (core keeps
                // the stream alive past it); fold it into the same first-error
                // slot as a provider error event and keep consuming so the
                // trailing Finish still lands (usage, recording).
                Err(error) if error.is_recoverable_stream_error() => {
                    if provider_error.is_none() {
                        provider_error = Some(error);
                    }
                    continue;
                }
                Err(error) => return Err(error),
            };
            if is_output_chunk(&part) {
                saw_output = true;
            }
            match part {
                StreamPart::TextStart {
                    provider_metadata, ..
                } => rm.text_start(provider_metadata),
                StreamPart::TextDelta {
                    delta,
                    provider_metadata,
                    ..
                } => {
                    text.push_str(&delta);
                    rm.text_delta(&delta, provider_metadata);
                }
                StreamPart::TextEnd {
                    provider_metadata, ..
                } => rm.text_end(provider_metadata),
                StreamPart::ReasoningStart {
                    provider_metadata, ..
                } => rm.reasoning_start(provider_metadata),
                StreamPart::ReasoningDelta {
                    delta,
                    provider_metadata,
                    ..
                } => rm.reasoning_delta(&delta, provider_metadata),
                StreamPart::ReasoningEnd {
                    provider_metadata, ..
                } => rm.reasoning_end(provider_metadata),
                StreamPart::ToolCall {
                    tool_call_id,
                    tool_name,
                    input,
                    provider_executed,
                    dynamic,
                    thought_signature,
                    provider_metadata,
                    invalid,
                    error,
                    ..
                } => {
                    let call = crate::tool::ToolCall {
                        tool_call_id,
                        tool_name,
                        input,
                        provider_executed,
                        dynamic,
                        thought_signature,
                        provider_metadata,
                        invalid,
                        error,
                    };
                    rm.tool_call(&call);
                    tool_calls.push(call);
                }
                StreamPart::ToolResult {
                    tool_call_id,
                    tool_name,
                    result,
                    is_error,
                    preliminary,
                    dynamic,
                    provider_metadata,
                } => rm.tool_result(
                    tool_call_id,
                    tool_name,
                    result,
                    is_error,
                    preliminary,
                    dynamic,
                    provider_metadata,
                ),
                StreamPart::Source {
                    id,
                    source_type,
                    url,
                    title,
                    ..
                } => {
                    sources.push(SourcePart {
                        id,
                        source_type,
                        url,
                        title,
                    });
                }
                StreamPart::File {
                    data, media_type, ..
                } => {
                    files.push(FilePart { data, media_type });
                }
                StreamPart::StreamStart { warnings: w, .. } => {
                    warnings = w;
                }
                StreamPart::Finish {
                    finish_reason: fr,
                    usage: u,
                    provider_metadata: pm,
                } => {
                    raw_finish_reason = fr.raw.clone();
                    finish_reason = fr;
                    usage = u.clone();
                    finish_provider_metadata = pm;
                    saw_finish = true;
                    break;
                }
                // Keep consuming after a provider error event: a trailing
                // Finish still carries usage for the recording layer. The
                // error is returned once the stream reaches its end.
                StreamPart::Error { error } if provider_error.is_none() => {
                    provider_error = Some(error);
                }
                StreamPart::ResponseMetadata {
                    id,
                    timestamp,
                    model_id,
                } => {
                    response = Some(crate::types::ResponseMetadata {
                        id,
                        timestamp,
                        model_id,
                    });
                }
                _ => {}
            }
        }

        if let Some(error) = provider_error {
            return Err(error);
        }
        if !saw_finish {
            // AI SDK semantics: an incomplete stream with no output at all is
            // an error; an incomplete stream with partial output retains the
            // partial result but must not claim a normal stop.
            if !saw_output {
                return Err(AiMuxError::InvalidResponseData(
                    "No output generated. The model stream ended without a finish chunk.".into(),
                ));
            }
            finish_reason = FinishReason {
                unified: crate::types::FinishReasonUnified::Other,
                raw: None,
            };
        }

        let crate::response_messages::ResponseMessages {
            messages: response_messages,
            reasoning,
        } = rm.finish();

        let reasoning_text = reasoning
            .iter()
            .map(|r| r.text.as_str())
            .collect::<Vec<_>>()
            .join("");

        Ok(StreamTextResultAggregated {
            text,
            reasoning,
            reasoning_text,
            tool_calls,
            sources,
            files,
            finish_reason,
            raw_finish_reason,
            total_usage: usage.clone(),
            usage,
            warnings,
            provider_metadata: finish_provider_metadata,
            response,
            response_messages,
        })
    }
}

// ─────────────────────────────────────────────────────────────────────────────
// User-facing functions
// ─────────────────────────────────────────────────────────────────────────────

/// Generate text (non-streaming).
///
/// # Example
///
/// ```no_run
/// use aimux_core::prelude::*;
///
/// # async fn example(model: &dyn LanguageModel) -> Result<(), AiMuxError> {
/// let result = generate_text(
///     model,
///     "What is Rust?",
///     GenerateTextOptions::default(),
/// ).await?;
///
/// println!("{}", result.text);
/// # Ok(())
/// # }
/// ```
///
/// # Errors
///
/// Returns the error produced by the model's `do_generate` call (provider API,
/// network, or abort).
pub async fn generate_text(
    model: &dyn LanguageModel,
    prompt: impl Into<ModelPrompt>,
    options: GenerateTextOptions,
) -> Result<GenerateTextResult, AiMuxError> {
    // 1. Convert user prompt to provider-facing prompt.
    let repair_tool_call = options.repair_tool_call.clone();
    let tools = options.tools.clone();
    let operation_instructions = options.instructions.clone();
    let (messages, instructions) = split_prompt(prompt.into(), operation_instructions.as_deref());
    let lm_prompt = convert_to_language_model_prompt(&messages, instructions);

    // 2. Build CallOptions.
    let mut call_options = options.into_call_options(lm_prompt);
    let operation_timeout =
        timeout::OperationTimeout::new(call_options.timeout.unwrap_or_default())?;
    let abort_signal = call_options.abort_signal.clone();
    let retries = retry::prepare_retries(
        call_options.max_retries,
        model.retry_config(),
        abort_signal.clone(),
    );

    // 2a. RFC-0023: 关闭时零成本(M2 评审)——仅在录制开启时生成 call_id
    //     并绑定 recorder 快照;传输封闭由层 A 收尾声明(P1 无层 B,barrier
    //     前提;P2 移交层 B)。
    let context = crate::recording::recorder().map(|recorder| {
        let call_id = crate::recording::new_call_id();
        call_options.call_id = Some(call_id.clone());
        let ctx = crate::recording::RecordingContext::new(call_id.clone(), recorder);
        call_options.recording_context = Some(ctx.clone());
        ctx.recorder.record_input(
            &ctx.call_id,
            &call_options,
            model.provider(),
            model.model_id(),
        );
        ctx.recorder
            .record_provider(&ctx.call_id, &model.config_snapshot());
        // 层 A 早发 closed(defense-in-depth):无 HTTP 的调用(mock/local)也
        // 能完成 barrier;真实 HTTP 的骨架 finalized=false 仍会挡写,由层 B
        // 结束再发 closed 完成。双发幂等。
        ctx.recorder.record_transport_closed(&ctx.call_id);
        ctx
    });
    let call_id = context.as_ref().map(|c| c.call_id.clone());
    let recorder = context.as_ref().map(|c| c.recorder.clone());

    // 2b. Session grouping (RFC-0024): explicit session_id first, opt-in
    //     prompt-prefix inference as fallback. Recorded before the call so
    //     failures are still part of the session. No-op unless a
    //     SessionStore is registered (init_session_store); the resolution
    //     and store lookups are cheap (once-locked env check + two RwLock
    //     reads) when no store / inferer is registered.
    if let (Some((session_id, source)), Some(store)) = (
        crate::session::resolve_session_id(
            call_options.session_id.as_deref(),
            &call_options.prompt,
        ),
        crate::session::session_store(),
    ) {
        let call = store.append(&session_id, call_options.call_id.as_deref(), source);
        // RFC-0024 P3: 录制带上会话归组信息(仅录制开启时有效;
        // recorder/call_id 同时存在才可能被写入)。
        if let (Some(recorder), Some(call_id)) = (&recorder, &call_id) {
            recorder.record_session(call_id, &session_id, call.step);
        }
    }

    // 3. Call provider, inside the "generate" span (RFC-0014 §4.1 span tree).
    //    The http layer's `http_request` span nests under this one.
    let started = Instant::now();
    let span = tracing::info_span!(
        target: "aimux_core::generate",
        "generate",
        provider = %model.provider(),
        model = %model.model_id(),
        modality = "text",
    );
    let operation = retries.retry(|| {
        if let Some(context) = &context {
            let _ = context.start_attempt();
        }
        do_generate_with_logging(model, &call_options, span.clone(), started)
    });
    let result = match timeout::run(operation, abort_signal.as_ref(), operation_timeout).await {
        Ok(r) => r,
        Err(e) => {
            if let (Some(rec), Some(call_id)) = (&recorder, &call_id) {
                rec.record_outcome(call_id, &crate::recording::OutcomeRecord::from_error(&e));
            }
            return Err(e);
        }
    };
    // 4. Extract text, tool calls, reasoning, sources, files from content.
    let mut text = String::new();
    let mut tool_calls = Vec::new();
    let mut sources = Vec::new();
    let mut files = Vec::new();
    // Build the assistant response message content parts in parallel.
    let mut rm = crate::response_messages::ResponseMessageBuilder::new();
    for content in &result.content {
        match content {
            GenerateContent::Text {
                text: t,
                provider_metadata,
            } => {
                text.push_str(t);
                rm.text(t, provider_metadata.as_ref());
            }
            GenerateContent::ToolCall {
                tool_call_id,
                tool_name,
                input,
                provider_executed,
                dynamic,
                thought_signature,
                provider_metadata,
                ..
            } => {
                let parsed = parse_tool_call(
                    RawToolCall {
                        tool_call_id: tool_call_id.clone(),
                        tool_name: tool_name.clone(),
                        input: input.clone(),
                        provider_executed: *provider_executed,
                        dynamic: *dynamic,
                        thought_signature: thought_signature.clone(),
                        provider_metadata: provider_metadata.clone(),
                    },
                    tools.as_deref(),
                    repair_tool_call.as_ref(),
                    &messages,
                    operation_instructions.as_deref(),
                )
                .await;
                rm.tool_call(&parsed);
                tool_calls.push(parsed);
            }
            GenerateContent::Reasoning {
                text: rtext,
                provider_metadata,
            } => {
                rm.reasoning(rtext, provider_metadata.as_ref());
            }
            GenerateContent::Source {
                id,
                source_type,
                url,
                title,
                ..
            } => {
                sources.push(SourcePart {
                    id: id.clone(),
                    source_type: source_type.clone(),
                    url: url.clone(),
                    title: title.clone(),
                });
            }
            GenerateContent::File {
                data, media_type, ..
            } => {
                files.push(FilePart {
                    data: data.clone(),
                    media_type: media_type.clone(),
                });
            }
            // Provider-executed results stay in the assistant message so the
            // provider can replay its own server-tool transcript next turn.
            GenerateContent::ToolResult {
                tool_call_id,
                tool_name,
                result,
                is_error,
                preliminary,
                dynamic,
                provider_metadata,
            } => {
                rm.tool_result(
                    tool_call_id.clone(),
                    tool_name.clone(),
                    result.clone(),
                    *is_error,
                    *preliminary,
                    *dynamic,
                    provider_metadata.clone(),
                );
            }
        }
    }

    let crate::response_messages::ResponseMessages {
        messages: response_messages,
        reasoning,
    } = rm.finish();
    let reasoning_text = reasoning
        .iter()
        .map(|r| r.text.as_str())
        .collect::<Vec<_>>()
        .join("");

    // Parsing and optional repair are part of the user operation. Record a
    // successful outcome only after that phase has completed within the same
    // deadline/cancellation scope as the provider call.
    if let (Some(rec), Some(call_id)) = (&recorder, &call_id) {
        rec.record_outcome(
            call_id,
            &crate::recording::OutcomeRecord::from_generate_result(&result),
        );
    }

    // Extract fields before moving `result` into `raw`.
    let raw_finish_reason = result.finish_reason.raw.clone();
    let provider_metadata = result.provider_metadata.clone();
    let response = result.response.clone();
    let usage = result.usage.clone();

    Ok(GenerateTextResult {
        text,
        tool_calls,
        finish_reason: result.finish_reason.clone(),
        usage: usage.clone(),
        warnings: result.warnings.clone(),
        raw: result,
        reasoning,
        reasoning_text,
        sources,
        files,
        response_messages,
        raw_finish_reason,
        provider_metadata,
        response,
        total_usage: usage,
    })
}

/// Generate a structured JSON object (M12). Uses `generate_text` with
/// `response_format: Json`, then parses the model output into a JSON value.
///
/// The schema is passed via `options.response_format = ResponseFormat::Json {
/// schema: Some(schema), .. }`. JSON repair (`fix_json`) is applied before
/// parsing to handle truncated or slightly malformed model output. No schema
/// validation is performed (weak validation — relies on the model following
/// the schema; use retries for robustness).
///
/// # Example
/// ```
/// # use aimux_core::prelude::*;
/// # use aimux_core::options::ResponseFormat;
/// # async fn example(model: &dyn aimux_core::LanguageModel) -> Result<(), aimux_core::error::AiMuxError> {
/// let result = generate_object(
///     model,
///     "Extract: John is 25 years old.",
///     GenerateTextOptions {
///         response_format: Some(ResponseFormat::Json {
///             schema: Some(serde_json::json!({
///                 "type": "object",
///                 "properties": { "name": { "type": "string" }, "age": { "type": "number" } },
///                 "required": ["name", "age"]
///             })),
///             name: None,
///             description: None,
///         }),
///         ..Default::default()
///     },
/// ).await?;
/// assert_eq!(result.object["name"], "John");
/// # Ok(())
/// # }
/// ```
///
/// # Errors
///
/// Propagates `generate_text` failures; additionally returns `JsonParse` when
/// the (repaired) model output is not valid JSON.
pub async fn generate_object(
    model: &dyn LanguageModel,
    prompt: impl Into<ModelPrompt>,
    options: GenerateTextOptions,
) -> Result<GenerateObjectResult, AiMuxError> {
    let text_result = generate_text(model, prompt, options).await?;
    let repaired = crate::json_repair::fix_json(&text_result.text);
    let object: Value = serde_json::from_str(&repaired).map_err(|e| {
        AiMuxError::JsonParse(format!(
            "generateObject: model output is not valid JSON after repair: {e}"
        ))
    })?;
    let raw_finish_reason = text_result.raw_finish_reason.clone();
    let finish_reason = text_result.finish_reason.clone();
    let usage = text_result.usage.clone();
    let warnings = text_result.warnings.clone();
    let reasoning = if text_result.reasoning_text.is_empty() {
        None
    } else {
        Some(text_result.reasoning_text.clone())
    };
    let provider_metadata = text_result.raw.provider_metadata.clone();
    let response = text_result.raw.response.clone();
    Ok(GenerateObjectResult {
        object,
        finish_reason,
        raw_finish_reason,
        usage,
        warnings,
        reasoning,
        provider_metadata,
        response,
        raw: text_result,
    })
}

/// Extract the reasoning signature from provider metadata, checking all known
/// provider keys (Anthropic, Bedrock).
/// Stream text from the model.
///
/// # Example
///
/// ```no_run
/// use aimux_core::prelude::*;
/// use futures::StreamExt;
///
/// # async fn example(model: &dyn LanguageModel) -> Result<(), AiMuxError> {
/// let result = stream_text(
///     model,
///     "Write a haiku about Rust.",
///     GenerateTextOptions::default(),
/// ).await?;
///
/// let mut stream = result.stream;
/// while let Some(part) = stream.next().await {
///     if let StreamPart::TextDelta { delta, .. } = part? {
///         print!("{}", delta);
///     }
/// }
/// # Ok(())
/// # }
/// ```
///
/// # Errors
///
/// Returns setup failures from the model's `do_stream` call. Provider error
/// events surface as `Ok(StreamPart::Error { .. })`; transport failures,
/// caller cancellation, and Core timeouts surface as `Err(AiMuxError)` stream
/// items.
pub async fn stream_text(
    model: &dyn LanguageModel,
    prompt: impl Into<ModelPrompt>,
    options: GenerateTextOptions,
) -> Result<StreamTextResult, AiMuxError> {
    // 1. Convert user prompt to provider-facing prompt.
    let repair_tool_call = options.repair_tool_call.clone();
    let tools = options.tools.clone();
    let operation_instructions = options.instructions.clone();
    let (messages, instructions) = split_prompt(prompt.into(), operation_instructions.as_deref());
    let lm_prompt = convert_to_language_model_prompt(&messages, instructions);

    // 2. Build CallOptions.
    let mut call_options = options.into_call_options(lm_prompt);
    let stream_timeout = call_options.timeout.unwrap_or_default();
    let operation_timeout = timeout::OperationTimeout::new(stream_timeout)?;
    // Armed at operation start: providers await their first SSE event inside
    // do_stream, so the first-chunk budget must already be counting there —
    // a 200-then-silence server is otherwise unbounded when only
    // first_chunk_ms is configured.
    let first_chunk_deadline = stream_timeout
        .first_chunk_ms
        .map(|duration_ms| timeout::TimeoutDeadline::from_now("First chunk", duration_ms))
        .transpose()?;
    let abort_signal = call_options.abort_signal.clone();
    let retries = retry::prepare_retries(
        call_options.max_retries,
        model.retry_config(),
        abort_signal.clone(),
    );

    // 2a. RFC-0023: 关闭时零成本(M2 评审)——仅在录制开启时生成 call_id
    //     并绑定 recorder 快照;传输封闭由层 A 收尾声明(P1 无层 B,barrier
    //     前提;P2 移交层 B)。
    let context = crate::recording::recorder().map(|recorder| {
        let call_id = crate::recording::new_call_id();
        call_options.call_id = Some(call_id.clone());
        let ctx = crate::recording::RecordingContext::new(call_id.clone(), recorder);
        call_options.recording_context = Some(ctx.clone());
        ctx.recorder.record_input(
            &ctx.call_id,
            &call_options,
            model.provider(),
            model.model_id(),
        );
        ctx.recorder
            .record_provider(&ctx.call_id, &model.config_snapshot());
        // 层 A 早发 closed(defense-in-depth):无 HTTP 的调用(mock/local)也
        // 能完成 barrier;真实 HTTP 的骨架 finalized=false 仍会挡写,由层 B
        // 结束再发 closed 完成。双发幂等。
        ctx.recorder.record_transport_closed(&ctx.call_id);
        ctx
    });
    let call_id = context.as_ref().map(|c| c.call_id.clone());
    let recorder = context.as_ref().map(|c| c.recorder.clone());

    // 2b. Session grouping (RFC-0024): explicit session_id first, opt-in
    //     prompt-prefix inference as fallback. Recorded before the call so
    //     failures are still part of the session. No-op unless a
    //     SessionStore is registered (init_session_store); the resolution
    //     and store lookups are cheap (once-locked env check + two RwLock
    //     reads) when no store / inferer is registered.
    if let (Some((session_id, source)), Some(store)) = (
        crate::session::resolve_session_id(
            call_options.session_id.as_deref(),
            &call_options.prompt,
        ),
        crate::session::session_store(),
    ) {
        let call = store.append(&session_id, call_options.call_id.as_deref(), source);
        // RFC-0024 P3: 录制带上会话归组信息(仅录制开启时有效;
        // recorder/call_id 同时存在才可能被写入)。
        if let (Some(recorder), Some(call_id)) = (&recorder, &call_id) {
            recorder.record_session(call_id, &session_id, call.step);
        }
    }

    // 3. Call provider, inside the "generate" span (RFC-0014 §4.1 span tree).
    let span = tracing::info_span!(
        target: "aimux_core::generate",
        "generate",
        provider = %model.provider(),
        model = %model.model_id(),
        modality = "text",
    );
    let operation = retries.retry(|| {
        if let Some(context) = &context {
            let _ = context.start_attempt();
        }
        // Call-level retry boundary: once do_stream returns a stream, retry
        // no longer recreates the provider request; the returned stream is
        // consumed by the stream-step timeout logic below.
        model.do_stream(&call_options).instrument(span.clone())
    });
    let setup_deadline = timeout::min_deadline(operation_timeout.deadline(), first_chunk_deadline);
    let result: StreamResult =
        match timeout::run_until(operation, abort_signal.as_ref(), setup_deadline).await {
            Ok(r) => r,
            Err(e) => {
                if let (Some(rec), Some(call_id)) = (&recorder, &call_id) {
                    rec.record_outcome(call_id, &crate::recording::OutcomeRecord::from_error(&e));
                }
                return Err(e);
            }
        };
    // 解构避免部分 move(result 各字段去向不同)。
    let StreamResult {
        stream,
        request_body,
        response_headers,
    } = result;

    // The consumption phase keeps observing the same deadlines: the
    // first-chunk budget armed at operation start continues until the first
    // output chunk.
    let operation_deadline = operation_timeout.deadline();
    // A pump task drives the provider stream, so the deadlines below measure
    // when provider output *arrives*: a deadline observed only inside
    // `poll_next` keeps elapsing while nobody polls, charging the provider
    // for the consumer's latency. The channel is unbounded so the pump never
    // blocks on the consumer (which would put that latency back into the
    // timers); the AI SDK's `streamText` consumes eagerly for the same
    // reason, and buffering is bounded by the response itself.
    //
    // Spawned even with no abort signal or deadlines armed: the pump is also
    // the stream's terminal fuse — `Finish` and non-recoverable errors must
    // end the stream under every configuration, or a provider that keeps the
    // connection open after `Finish` hangs a consumer reading to end-of-stream.
    let stream: Pin<Box<dyn Stream<Item = Result<StreamPart, AiMuxError>> + Send>> = {
        let mut stream = stream;
        let chunk_ms = stream_timeout.chunk_ms;
        let pump_abort = abort_signal.clone();
        let (tx, mut rx) = tokio::sync::mpsc::unbounded_channel();
        let pump = tokio::spawn(async move {
            let mut chunk_deadline = first_chunk_deadline;

            loop {
                let next = tokio::select! {
                    biased;
                    // Dropping the provider stream cancels the in-flight HTTP
                    // exchange; the consumer side reports the abort error.
                    () = timeout::wait_for_abort(pump_abort.as_ref()) => break,
                    () = timeout::wait_for_deadline(operation_deadline) => {
                        let _ = tx.send(Err(operation_deadline
                            .expect("operation deadline future only resolves for a deadline")
                            .error()));
                        break;
                    }
                    () = timeout::wait_for_deadline(chunk_deadline) => {
                        let _ = tx.send(Err(chunk_deadline
                            .expect("chunk deadline future only resolves for a deadline")
                            .error()));
                        break;
                    }
                    item = stream.next() => item,
                };

                let Some(item) = next else { break };
                let terminal = is_terminal_item(&item);
                if let Ok(part) = &item
                    && is_output_chunk(part)
                {
                    chunk_deadline = match chunk_ms
                        .map(|duration_ms| timeout::TimeoutDeadline::from_now("Chunk", duration_ms))
                        .transpose()
                    {
                        Ok(deadline) => deadline,
                        Err(error) => {
                            let _ = tx.send(Err(error));
                            break;
                        }
                    };
                }

                // A closed receiver means the consumer dropped the stream.
                if tx.send(item).is_err() || terminal {
                    break;
                }
            }
        });
        let pump = AbortOnDrop(pump);
        Box::pin(async_stream::stream! {
            let _pump = pump;
            loop {
                let next = tokio::select! {
                    biased;
                    () = timeout::wait_for_abort(abort_signal.as_ref()) => {
                        yield Err(AiMuxError::from_abort_signal(
                            abort_signal.as_ref().expect("abort future only resolves for a signal"),
                        ));
                        break;
                    }
                    item = rx.recv() => item,
                };
                let Some(item) = next else { break };
                // Mirror the pump's fuse here so the stream ends right after
                // the terminal item, ahead of a later abort or the channel
                // close racing it.
                let terminal = is_terminal_item(&item);
                yield item;
                if terminal {
                    break;
                }
            }
        })
    };
    let mut stream = stream;
    let stream: Pin<Box<dyn Stream<Item = Result<StreamPart, AiMuxError>> + Send>> =
        Box::pin(async_stream::stream! {
            while let Some(item) = stream.next().await {
                match item {
                    Ok(StreamPart::ToolCall {
                        tool_call_id,
                        tool_name,
                        input,
                        provider_executed,
                        dynamic,
                        thought_signature,
                        provider_metadata,
                        ..
                    }) => {
                        let parsed = parse_tool_call(
                            RawToolCall {
                                tool_call_id,
                                tool_name,
                                input: crate::parse_tool_call::raw_tool_input(&input),
                                provider_executed,
                                dynamic,
                                thought_signature,
                                provider_metadata,
                            },
                            tools.as_deref(),
                            repair_tool_call.as_ref(),
                            &messages,
                            operation_instructions.as_deref(),
                        ).await;
                        yield Ok(StreamPart::ToolCall {
                            tool_call_id: parsed.tool_call_id,
                            tool_name: parsed.tool_name,
                            input: parsed.input,
                            provider_executed: parsed.provider_executed,
                            dynamic: parsed.dynamic,
                            thought_signature: parsed.thought_signature,
                            invalid: parsed.invalid,
                            error: parsed.error,
                            provider_metadata: parsed.provider_metadata,
                        });
                    }
                    item => yield item,
                }
            }
        });
    // 录制开启时才包装(终结时写 outcome + 传输封闭);关闭时零成本透传。
    let stream = crate::recording::RecordingOutcomeStream::new(
        stream,
        recorder.clone(),
        call_id.unwrap_or_default(),
    );

    // 4. Return wrapped stream to user (request_body/response_headers kept for
    //    debugging / cache probing, RFC-0015).
    Ok(StreamTextResult {
        stream: Box::pin(stream),
        request_body,
        response_headers,
    })
}

/// A malformed individual frame does not prove that the transport is dead:
/// SSE framing lets a later event still be valid. `Finish` and transport/Core
/// errors are terminal so the stream is not polled past a dead source.
fn is_terminal_item(item: &Result<StreamPart, AiMuxError>) -> bool {
    matches!(item, Ok(StreamPart::Finish { .. }))
        || matches!(item, Err(error) if !error.is_recoverable_stream_error())
}

/// Aborts the stream pump task when the returned stream is dropped, so an
/// abandoned stream leaves no task driving the provider connection.
struct AbortOnDrop(tokio::task::JoinHandle<()>);

impl Drop for AbortOnDrop {
    fn drop(&mut self) {
        self.0.abort();
    }
}
/// Run `do_generate` inside the RFC-0014 `generate` span and emit the
/// `generate_end` event. A plain async fn (rather than an inline async block)
/// so the `?` error type is pinned by the declared return type.
async fn do_generate_with_logging(
    model: &dyn LanguageModel,
    call_options: &CallOptions,
    span: tracing::Span,
    started: Instant,
) -> Result<GenerateResult, AiMuxError> {
    let r = async { model.do_generate(call_options).await }
        .instrument(span)
        .await?;
    tracing::info!(
        target: "aimux_core::generate",
        ok = true,
        duration_ms = started.elapsed().as_millis() as u64,
        finish_reason = ?r.finish_reason.unified,
        "generate_end"
    );
    Ok(r)
}

/// Split a `ModelPrompt` into messages + optional instructions.
///
/// If the prompt is a plain string, it becomes a single user message.
/// If the prompt is messages, they are used as-is.
/// Instructions are passed through separately (they get prepended by
/// `convert_to_language_model_prompt`).
pub(crate) fn split_prompt(
    prompt: ModelPrompt,
    instructions: Option<&str>,
) -> (Vec<ModelMessage>, Option<&str>) {
    match prompt {
        ModelPrompt::Text(text) => (vec![ModelMessage::user(text)], instructions),
        ModelPrompt::Messages(msgs) => (msgs, instructions),
    }
}

// ─────────────────────────────────────────────────────────────────────────────
// OpenAI Chat Completions output (RFC-0026)
// ─────────────────────────────────────────────────────────────────────────────

use crate::openai_output::{
    ChatCompletion, ChatCompletionFunction, ChatCompletionStream, ChatCompletionToolCall,
    OpenAiStreamOptions, parsed_tool_call_arguments, to_chat_completion, to_chat_completion_stream,
};

/// Generate text and return the result as an OpenAI Chat Completion.
///
/// This is the OpenAI-compatible equivalent of [`generate_text`]. Internally
/// it calls `generate_text`, then converts the [`GenerateResult`] into a
/// [`ChatCompletion`] via [`to_chat_completion`].
/// Tool calls reflect Core parsing and any configured repair; provider
/// response metadata, usage, and non-tool content are preserved from `raw`.
///
/// Works with **any** provider (OpenAI, Anthropic, Google, …) — the output is
/// always standard OpenAI Chat Completions JSON.
///
/// # Example
///
/// ```no_run
/// use aimux_core::prelude::*;
///
/// # async fn example(model: &dyn LanguageModel) -> Result<(), AiMuxError> {
/// let completion = generate_text_as_openai(
///     model,
///     "What is Rust?",
///     GenerateTextOptions::default(),
/// ).await?;
///
/// println!("{}", completion.choices[0].message.content.as_deref().unwrap());
/// println!("{}", completion.usage.prompt_tokens);
/// # Ok(())
/// # }
/// ```
///
/// # Errors
///
/// Propagates any error from the underlying `generate_text` call.
pub async fn generate_text_as_openai(
    model: &dyn LanguageModel,
    prompt: impl Into<ModelPrompt>,
    options: GenerateTextOptions,
) -> Result<ChatCompletion, AiMuxError> {
    let result = generate_text(model, prompt, options).await?;
    Ok(generate_text_result_to_chat_completion(
        &result,
        model.model_id(),
    ))
}

/// Convert a [`GenerateTextResult`] into an OpenAI [`ChatCompletion`].
///
/// The pure half of [`generate_text_as_openai`]: tool calls come from
/// `result.tool_calls` (so they reflect Core parsing and any repair already
/// applied to the result), everything else from `result.raw` via
/// [`to_chat_completion`]. Hosts that repair a result themselves (RFC-0035)
/// convert it with this afterwards.
///
/// `model_id` is the fallback for `ChatCompletion.model` when the provider
/// response carries no model id.
#[must_use]
pub fn generate_text_result_to_chat_completion(
    result: &GenerateTextResult,
    model_id: &str,
) -> ChatCompletion {
    let mut completion = to_chat_completion(&result.raw, model_id);
    if let Some(choice) = completion.choices.first_mut() {
        choice.message.tool_calls = if result.tool_calls.is_empty() {
            None
        } else {
            Some(
                result
                    .tool_calls
                    .iter()
                    .map(|tool_call| ChatCompletionToolCall {
                        id: tool_call.tool_call_id.clone(),
                        tool_type: "function".to_string(),
                        function: ChatCompletionFunction {
                            name: tool_call.tool_name.clone(),
                            arguments: parsed_tool_call_arguments(
                                &tool_call.input,
                                tool_call.invalid,
                                tool_call.error.as_ref(),
                            ),
                        },
                    })
                    .collect(),
            )
        };
    }
    completion
}

/// Stream text and return the result as a stream of OpenAI Chat Completion chunks.
///
/// This is the OpenAI-compatible equivalent of [`stream_text`]. Internally
/// it calls `stream_text`, then converts the `StreamPart` stream into a
/// `ChatCompletionChunk` stream via [`to_chat_completion_stream`].
///
/// Works with **any** provider (OpenAI, Anthropic, Google, …) — the output is
/// always standard OpenAI Chat Completions streaming chunks.
///
/// Tool-call argument deltas are the provider's text, forwarded verbatim as it
/// arrives, so this stream does **not** reflect tool-call repair — aligned
/// with the AI SDK, which likewise never withholds input deltas. Use
/// [`generate_text_as_openai`] or the native `stream_text` when repaired calls
/// are required.
///
/// # Example
///
/// ```no_run
/// use aimux_core::prelude::*;
/// use futures::StreamExt;
///
/// # async fn example(model: &dyn LanguageModel) -> Result<(), AiMuxError> {
/// let result = stream_text_as_openai(
///     model,
///     "Write a haiku about Rust.",
///     GenerateTextOptions::default(),
///     OpenAiStreamOptions::default(),
/// ).await?;
///
/// let mut stream = result.stream;
/// while let Some(chunk) = stream.next().await {
///     let chunk = chunk?;
///     if let Some(delta) = chunk.choices.first()
///         && let Some(content) = &delta.delta.content {
///         print!("{}", content);
///     }
/// }
/// # Ok(())
/// # }
/// ```
///
/// # Errors
///
/// Propagates any error from the underlying `stream_text` call.
pub async fn stream_text_as_openai(
    model: &dyn LanguageModel,
    prompt: impl Into<ModelPrompt>,
    options: GenerateTextOptions,
    stream_options: OpenAiStreamOptions,
) -> Result<ChatCompletionStream, AiMuxError> {
    let result = stream_text(model, prompt, options).await?;
    Ok(to_chat_completion_stream(
        result.stream,
        model.model_id(),
        stream_options,
    ))
}

#[cfg(test)]
mod operation_retry_tests {
    use std::sync::atomic::{AtomicUsize, Ordering};

    use async_trait::async_trait;

    use super::*;
    use crate::{ApiCallError, LanguageModel, prelude::StreamPart};

    enum StreamBehavior {
        Normal,
        FinishThenPending,
        ProviderErrorThenFinish,
        ParseErrorThenEvent,
        TransportErrorThenPending,
        NeverReturns,
        RetryableFirstError,
        NonRetryableFirstError,
    }

    struct StreamModel {
        behavior: StreamBehavior,
        calls: AtomicUsize,
    }

    impl StreamModel {
        fn new(behavior: StreamBehavior) -> Self {
            Self {
                behavior,
                calls: AtomicUsize::new(0),
            }
        }

        fn api_error(status: u16, retryable: bool) -> AiMuxError {
            AiMuxError::ApiCall(Box::new(ApiCallError {
                status_code: Some(status),
                response_headers: Some(HashMap::from([("retry-after-ms".into(), "0".into())])),
                is_retryable: retryable,
                ..ApiCallError::new(
                    "stream setup failed",
                    "https://example.test/stream",
                    serde_json::json!({}),
                )
            }))
        }

        fn single_event_stream() -> StreamResult {
            StreamResult {
                stream: Box::pin(futures::stream::iter([Ok(StreamPart::TextDelta {
                    id: "text-1".into(),
                    delta: "hello".into(),
                    provider_metadata: None,
                })])),
                request_body: None,
                response_headers: None,
            }
        }

        fn finish_stream() -> StreamResult {
            let finish = StreamPart::Finish {
                finish_reason: crate::types::FinishReason {
                    unified: crate::types::FinishReasonUnified::Stop,
                    raw: Some("stop".into()),
                },
                usage: Usage::default(),
                provider_metadata: None,
            };
            StreamResult {
                stream: Box::pin(
                    futures::stream::iter([Ok(finish)]).chain(futures::stream::pending()),
                ),
                request_body: None,
                response_headers: None,
            }
        }

        fn provider_error_then_finish_stream() -> StreamResult {
            let finish = StreamPart::Finish {
                finish_reason: crate::types::FinishReason {
                    unified: crate::types::FinishReasonUnified::Error,
                    raw: None,
                },
                usage: Usage::default(),
                provider_metadata: None,
            };
            StreamResult {
                stream: Box::pin(
                    futures::stream::iter([
                        Ok(StreamPart::Error {
                            error: AiMuxError::Other("provider error".into()),
                        }),
                        Ok(finish),
                    ])
                    .chain(futures::stream::pending()),
                ),
                request_body: None,
                response_headers: None,
            }
        }

        fn parse_error_then_event_stream() -> StreamResult {
            StreamResult {
                stream: Box::pin(futures::stream::iter([
                    Err(AiMuxError::JsonParse("malformed SSE data".into())),
                    Ok(StreamPart::TextDelta {
                        id: "text-1".into(),
                        delta: "after-error".into(),
                        provider_metadata: None,
                    }),
                ])),
                request_body: None,
                response_headers: None,
            }
        }
    }

    #[async_trait]
    impl LanguageModel for StreamModel {
        fn provider(&self) -> &str {
            "test"
        }

        fn model_id(&self) -> &str {
            "stream-model"
        }

        async fn do_generate(&self, _options: &CallOptions) -> Result<GenerateResult, AiMuxError> {
            Err(AiMuxError::Other("unused".into()))
        }

        async fn do_stream(&self, _options: &CallOptions) -> Result<StreamResult, AiMuxError> {
            let attempt = self.calls.fetch_add(1, Ordering::SeqCst);
            match self.behavior {
                StreamBehavior::Normal => Ok(Self::single_event_stream()),
                StreamBehavior::FinishThenPending => Ok(Self::finish_stream()),
                StreamBehavior::ProviderErrorThenFinish => {
                    Ok(Self::provider_error_then_finish_stream())
                }
                StreamBehavior::ParseErrorThenEvent => Ok(Self::parse_error_then_event_stream()),
                StreamBehavior::TransportErrorThenPending => Ok(StreamResult {
                    stream: Box::pin(
                        futures::stream::iter([Err(AiMuxError::ApiCall(Box::new(ApiCallError {
                            is_retryable: true,
                            ..ApiCallError::new(
                                "connection reset",
                                "https://example.test/stream",
                                serde_json::json!({}),
                            )
                        })))])
                        .chain(futures::stream::pending()),
                    ),
                    request_body: None,
                    response_headers: None,
                }),
                StreamBehavior::NeverReturns => std::future::pending().await,
                StreamBehavior::RetryableFirstError if attempt == 0 => {
                    Err(Self::api_error(429, true))
                }
                StreamBehavior::RetryableFirstError => Ok(Self::single_event_stream()),
                StreamBehavior::NonRetryableFirstError => Err(Self::api_error(400, false)),
            }
        }
    }

    fn retry_options() -> GenerateTextOptions {
        GenerateTextOptions {
            max_retries: Some(2),
            ..Default::default()
        }
    }

    #[tokio::test]
    async fn stream_setup_preserves_the_peeked_first_event() {
        let model = StreamModel::new(StreamBehavior::Normal);
        let mut result = stream_text(&model, "hello", retry_options()).await.unwrap();
        let first = result.stream.next().await.unwrap().unwrap();
        assert!(matches!(first, StreamPart::TextDelta { delta, .. } if delta == "hello"));
        assert!(result.stream.next().await.is_none());
    }

    #[tokio::test]
    async fn late_consumer_still_receives_a_first_chunk_delivered_on_time() {
        // The provider yields immediately; the first-chunk budget measures
        // that arrival, not when the caller gets around to polling. Sleeping
        // past the budget before the first poll must not turn delivered
        // output into a timeout.
        let model = StreamModel::new(StreamBehavior::Normal);
        let options = GenerateTextOptions {
            max_retries: Some(0),
            timeout: Some(crate::options::TimeoutConfiguration {
                first_chunk_ms: Some(1),
                ..Default::default()
            }),
            ..Default::default()
        };
        let mut result = stream_text(&model, "hello", options).await.unwrap();

        tokio::time::sleep(std::time::Duration::from_millis(20)).await;

        assert!(matches!(
            result.stream.next().await.unwrap().unwrap(),
            StreamPart::TextDelta { delta, .. } if delta == "hello"
        ));
        assert!(result.stream.next().await.is_none());
    }

    #[tokio::test]
    async fn caller_abort_still_cancels_the_returned_stream() {
        let model = StreamModel::new(StreamBehavior::Normal);
        let abort_signal = AbortSignal::new();
        let options = GenerateTextOptions {
            max_retries: Some(0),
            abort_signal: Some(abort_signal.clone()),
            ..Default::default()
        };
        let mut result = stream_text(&model, "hello", options).await.unwrap();

        abort_signal.abort();

        assert!(matches!(
            result.stream.next().await.unwrap(),
            Err(AiMuxError::Aborted(message)) if message == "request aborted"
        ));
    }

    #[tokio::test]
    async fn terminal_stream_part_stops_stream_consumption() {
        let model = StreamModel::new(StreamBehavior::FinishThenPending);
        let options = GenerateTextOptions {
            max_retries: Some(0),
            timeout: Some(crate::options::TimeoutConfiguration {
                total_ms: Some(50),
                ..Default::default()
            }),
            ..Default::default()
        };
        let mut result = stream_text(&model, "hello", options).await.unwrap();

        assert!(matches!(
            result.stream.next().await.unwrap().unwrap(),
            StreamPart::Finish { .. }
        ));
        tokio::time::sleep(std::time::Duration::from_millis(60)).await;
        assert!(result.stream.next().await.is_none());
    }

    #[tokio::test]
    async fn provider_error_part_does_not_hide_the_final_finish() {
        let model = StreamModel::new(StreamBehavior::ProviderErrorThenFinish);
        let abort_signal = AbortSignal::new();
        let options = GenerateTextOptions {
            max_retries: Some(0),
            abort_signal: Some(abort_signal.clone()),
            ..Default::default()
        };
        let mut result = stream_text(&model, "hello", options).await.unwrap();

        assert!(matches!(
            result.stream.next().await.unwrap().unwrap(),
            StreamPart::Error { .. }
        ));
        assert!(matches!(
            result.stream.next().await.unwrap().unwrap(),
            StreamPart::Finish { finish_reason, .. }
                if finish_reason.unified == crate::types::FinishReasonUnified::Error
        ));
        abort_signal.abort();
        assert!(result.stream.next().await.is_none());
    }

    #[tokio::test]
    async fn timeout_wrapper_continues_after_a_malformed_stream_frame() {
        let model = StreamModel::new(StreamBehavior::ParseErrorThenEvent);
        let options = GenerateTextOptions {
            max_retries: Some(0),
            timeout: Some(crate::options::TimeoutConfiguration {
                total_ms: Some(1_000),
                ..Default::default()
            }),
            ..Default::default()
        };
        let mut result = stream_text(&model, "hello", options).await.unwrap();

        assert!(matches!(
            result.stream.next().await.unwrap(),
            Err(AiMuxError::JsonParse(_))
        ));
        assert!(matches!(
            result.stream.next().await.unwrap().unwrap(),
            StreamPart::TextDelta { delta, .. } if delta == "after-error"
        ));
    }

    #[tokio::test]
    async fn abort_wrapper_continues_after_a_malformed_stream_frame() {
        let model = StreamModel::new(StreamBehavior::ParseErrorThenEvent);
        let options = GenerateTextOptions {
            max_retries: Some(0),
            abort_signal: Some(AbortSignal::new()),
            ..Default::default()
        };
        let mut result = stream_text(&model, "hello", options).await.unwrap();

        assert!(matches!(
            result.stream.next().await.unwrap(),
            Err(AiMuxError::JsonParse(_))
        ));
        assert!(matches!(
            result.stream.next().await.unwrap().unwrap(),
            StreamPart::TextDelta { delta, .. } if delta == "after-error"
        ));
    }

    #[tokio::test]
    async fn first_chunk_timeout_bounds_the_stream_setup_phase() {
        // Providers await their first SSE event inside do_stream; a
        // 200-then-silence server must be bounded by first_chunk_ms alone.
        let model = StreamModel::new(StreamBehavior::NeverReturns);
        let options = GenerateTextOptions {
            max_retries: Some(0),
            timeout: Some(crate::options::TimeoutConfiguration {
                first_chunk_ms: Some(5),
                ..Default::default()
            }),
            ..Default::default()
        };
        let error = stream_text(&model, "hello", options).await.unwrap_err();
        assert!(
            matches!(error, AiMuxError::Timeout(ref message) if message == "First chunk timeout of 5ms exceeded"),
            "got {error:?}"
        );
    }

    #[tokio::test]
    async fn transport_error_ends_the_wrapped_stream() {
        let model = StreamModel::new(StreamBehavior::TransportErrorThenPending);
        let abort_signal = AbortSignal::new();
        let options = GenerateTextOptions {
            max_retries: Some(0),
            abort_signal: Some(abort_signal.clone()),
            ..Default::default()
        };
        let mut result = stream_text(&model, "hello", options).await.unwrap();

        assert!(matches!(
            result.stream.next().await.unwrap(),
            Err(AiMuxError::ApiCall(_))
        ));
        // Without treating Err as terminal this next() would hang on the
        // pending tail of the dead source stream.
        assert!(result.stream.next().await.is_none());
    }

    #[tokio::test]
    async fn retryable_first_stream_error_retries_before_returning_stream() {
        let model = StreamModel::new(StreamBehavior::RetryableFirstError);
        let mut result = stream_text(&model, "hello", retry_options()).await.unwrap();
        assert_eq!(model.calls.load(Ordering::SeqCst), 2);
        assert!(matches!(
            result.stream.next().await.unwrap().unwrap(),
            StreamPart::TextDelta { delta, .. } if delta == "hello"
        ));
    }

    #[tokio::test]
    async fn non_retryable_first_stream_error_is_returned_unchanged() {
        let model = StreamModel::new(StreamBehavior::NonRetryableFirstError);
        let error = stream_text(&model, "hello", retry_options())
            .await
            .unwrap_err();
        assert!(
            matches!(error, AiMuxError::ApiCall(ref detail) if detail.status_code == Some(400))
        );
        assert_eq!(model.calls.load(Ordering::SeqCst), 1);
    }
}

#[cfg(test)]
mod stream_aggregation_tests {
    use super::*;
    use crate::types::FinishReasonUnified;

    fn result_from(parts: Vec<Result<StreamPart, AiMuxError>>) -> StreamTextResult {
        StreamTextResult {
            stream: Box::pin(futures::stream::iter(parts)),
            request_body: None,
            response_headers: None,
        }
    }

    fn delta(text: &str) -> StreamPart {
        StreamPart::TextDelta {
            id: "text-1".into(),
            delta: text.into(),
            provider_metadata: None,
        }
    }

    fn finish() -> StreamPart {
        StreamPart::Finish {
            finish_reason: FinishReason {
                unified: FinishReasonUnified::Stop,
                raw: Some("stop".into()),
            },
            usage: Usage::default(),
            provider_metadata: None,
        }
    }

    #[tokio::test]
    async fn truncated_stream_with_partial_output_does_not_claim_a_normal_stop() {
        let result = result_from(vec![Ok(delta("par"))]).consume().await.unwrap();
        assert_eq!(result.text, "par");
        assert_eq!(result.finish_reason.unified, FinishReasonUnified::Other);

        // text() retains the partial result (AI SDK semantics).
        let text = result_from(vec![Ok(delta("par"))]).text().await.unwrap();
        assert_eq!(text, "par");
    }

    #[tokio::test]
    async fn empty_incomplete_stream_is_an_error() {
        let error = result_from(vec![]).consume().await.unwrap_err();
        assert!(
            matches!(&error, AiMuxError::InvalidResponseData(message) if message.contains("without a finish chunk"))
        );
        let error = result_from(vec![]).text().await.unwrap_err();
        assert!(matches!(error, AiMuxError::InvalidResponseData(_)));
    }

    #[tokio::test]
    async fn stream_with_finish_still_reports_the_provider_finish_reason() {
        let result = result_from(vec![Ok(delta("hi")), Ok(finish())])
            .consume()
            .await
            .unwrap();
        assert_eq!(result.finish_reason.unified, FinishReasonUnified::Stop);
    }

    #[tokio::test]
    async fn provider_error_still_wins_after_draining_a_trailing_finish() {
        let parts = vec![
            Ok(delta("partial")),
            Ok(StreamPart::Error {
                error: AiMuxError::Other("provider error".into()),
            }),
            Ok(finish()),
        ];
        let error = result_from(parts).consume().await.unwrap_err();
        assert!(matches!(error, AiMuxError::Other(message) if message == "provider error"));
    }
}